WASHINGTON (CNN) --President Bush Wednesday hailed what he called a "major, significant find" in the war against terrorism -- the arrest in Pakistan of a top al Qaeda operative believed to have played roles in the September 11, 2001, attacks and the bombing of the USS Cole.

Whalid ba Attash, also known as Tawfiq bin Attash or Khallad, was arrested Tuesday along with five other suspected al Qaeda members in a police raid in the port city of Karachi, Pakistan's Information Ministry said.

"He's a killer. He was one of the top al Qaeda operatives," Bush said at the White House. "He was right below Khalid Shaikh Mohammed on the organizational chart of al Qaeda. He is one less person that people who love freedom have to worry about."

A senior Pakistani officer, who did not want to be named, said that when authorities arrested the six men, they were planning to attack the U.S. consulate and other government installations in Karachi.

Pakistani authorities identified Attash as a Yemeni national and said his arrest averted a "major terrorist attack."

Police found 150 kilograms (330 pounds) of high explosives and a large quantity of guns and ammunition when he was arrested, the Information Ministry said.

Bush praised Pakistan for its role in apprehending Attash and said the coalition is winning the war on terror.

"When al Qaeda came and killed Americans, there was only one way to deal with them: That was to hunt them down, find them and bring them to justice," Bush said. "The war goes on."

U.S. officials also believe Attash was the mastermind of the Cole bombing, which killed 17 U.S. sailors October 12, 2000.

One U.S. official said Attash -- once a bodyguard to al Qaeda leader Osama bin Laden -- "will know about future al Qaeda plans."

Attash is believed to be "very close" to bin Laden and served as an intermediary between Khalid Shaikh Mohammed, the September 11 plot's mastermind, and some of the hijackers.

The September 11 attacks on New York and Washington and Pennsylvania killed more than 3,000 people and triggered the U.S. war to oust al Qaeda from Afghanistan, where Attash is believed to have lost a leg in combat.

No U.S. officials were present at the time of his capture, though officials in Washington said U.S. intelligence provided "information that may have been helpful" in the operation.

CNN National Security Correspondent David Ensor and Producer Syed Mohsin Naqvi contributed to this report.